When the valve is in the right position, the total motion from forward to reverse is 90 degrees. So when it is in neutral its in the middle, and it goes 45 degree one way for forward, or goes 45 degress the other way for reverse.
If the valve is the wrong position, it has to turn around further to line up the oil passages and work.
I have not had one of these apart. did you take the lever off the end of the valve? Are there flats on the vave shaft? If so will the lever go on either way? That's what I was wondering about.
If the lever will go back on either way, take it off, turn the valve 1/2 turn, and put the lever back on - ??
Sorry if I'm missing the point here, but when you said it works but has to go too far, the valve being rotated out of position is all I could think of.
I would not think the valve has to come out (or should).
Another possibility would be if the lever is pointing the wrong way? The hole for the operating rod goes inboard toward the tractor, right?